Torque wrench

Abstract

A torque wrench includes a driving head, a hollow handle, compression unit, an adjustment unit, an index unit and a display unit. The driving head and the handle are pivotably connected to each other. The compression unit has a resilient member and an end piece which contacts the driving head. The adjustment unit adjusts the length of the resilient member to set the torque of the wrench. The index unit has a first index and a second index, both of which are moved with the movement of the adjustment unit. The movement of the first index is detected by the display unit and transferred into digits to display the value of the torque. The second index is cooperated with the marks of the scale member to display the value of the torque.

What is claimed is: 
     
       1. A torque wrench comprising:
 a hollow handle having a space defined therein; 
 a driving head having a shank extending therefrom which is inserted into the space, the shank pivotably connected to the handle by a pin and the shank being pivotable within the space; 
 a compression unit located in the space and having a resilient member and end piece, the resilient member having a first end contacting the end piece and the end piece contacting a distal end of the shank; 
 an adjustment unit connected to the handle to adjust the resilient member to reach a torque value of the driving head; the adjustment unit has an outer tube and an adjustment rod which is movably located in the handle, the outer tube is rotatably mounted to the handle and has a threaded hole, the adjustment rod has a threaded section which is engaged with the threaded hole, when the outer tube is rotated relative to the handle, the adjustment rod moves axially to change a length of the resilient member and move the second piece; 
 an index unit having a second piece, a first index and a second index, the second piece, the first index and the second index being an integral part and movable longitudinally with a length change of the resilient member; 
 a display unit fixed to the handle and having a display member, a calculation member and at least one movement sensor which detects a movement distance of the first index and generates a signal which is calculated by the calculation member and transferred into a torque value displayed in the display member, and 
 a scale member being a transparent member and having marks thereon, the scale member located to the handle and corresponding to the second index, the mark being pointed by the second index being the torque value. 
 
     
     
       2. The torque wrench as claimed in  claim 1 , wherein there are four movement sensors and the first index has multiple parallel first lines and second lines, the first and the second lines are detected by the movement sensors. 
     
     
       3. The torque wrench as claimed in  claim 1 , wherein the handle has at least one ring fixed therein and the at least one ring has a slot defined in an outer surface thereof and the first index movably engaged with the slot, the resilient member extends through the at least one ring. 
     
     
       4. The torque wrench as claimed in  claim 1 , wherein the first index has value marks which are matched with the marks on the scale member. 
     
     
       5. The torque wrench as claimed in  claim 1 , wherein the second index is located above the first index. 
     
     
       6. The torque wrench as claimed in  claim 1 , wherein the handle includes a guide slot and the second piece is movably mounted to the adjustment rod, the second piece has a positioning member which is located in the guide slot. 
     
     
       7. The torque wrench as claimed in  claim 6 , wherein the adjustment rod has a groove defined in an outer surface thereof and a clip is engaged with the groove to contact the second piece so that the second piece is movably mounted to the adjustment rod. 
     
     
       8. A torque wrench comprising:
 a hollow handle having a space defined therein; 
 a driving head having a shank extending therefrom which is inserted into the space, the shank pivotably connected to the handle by a pin and the shank being pivotable within the space 
 a compression unit located in the space and having a resilient member and end piece, the resilient member having a first end contacting the end piece and the end piece contacting a distal end of the shank; 
 an adjustment unit connected to the handle to adjust the resilient member to reach a torque value of the driving head; the adjustment unit has a fixing block, an outer tube, an adjustment rod and a clip, the fixing block is fixed in the space and includes a threaded hole defined centrally therethrough, the outer tube is rotatably mounted to the handle and has an end with a hexagonal hole defined centrally therethrough, the adjustment rod has a threaded section which is engaged with the threaded hole, a first piece is connected to an end of the threaded section and contacts a second end of the resilient member, the first piece has a hexagonal block extends from a distal end of the threaded section and is engaged with the hexagonal hole, the clip is engaged with a distal end of the threaded section to connect the outer tube to the adjustment rod, when the outer tube is rotated relative to the handle, the adjustment rod moves axially to change a length of the resilient member and move the second piece; 
 an index unit having a second piece, a first index and a second index, the second piece, the first index and the second index being an integral part and movable longitudinally with a length change of the resilient member; 
 a display unit fixed to the handle and having a display member, a calculation member and at least one movement sensor which detects a movement distance of the first index and generates a signal which is calculated by the calculation member and transferred into a torque value displayed in the display member, and 
 a scale member being a transparent member and having marks thereon, the scale member located to the handle and corresponding to the second index, the mark being pointed by the second index being the torque value. 
 
     
     
       9. The torque wrench as claimed in  claim 8 , wherein the handle includes a guide slot and the second piece is movably mounted to the adjustment rod, the second piece has a positioning member which is located in the guide slot. 
     
     
       10. The torque wrench as claimed in  claim 9 , wherein the adjustment rod has a groove defined in an outer surface thereof and a clip is engaged with the groove to contact the second piece so that the second piece is movably mounted to the adjustment rod. 
     
     
       11. A torque wrench comprising:
 a hollow handle having a space defined therein; the handle has at least one ring fixed therein and the at least one ring has a slot defined in an outer surface thereof; 
 a driving head having a shank extending therefrom which is inserted into the space, the shank pivotably connected to the handle by a pin and the shank being pivotable within the space; 
 a compression unit located in the space and having a resilient member and end piece, the resilient member having a first end contacting the end piece and the end piece contacting a distal end of the shank; 
 an adjustment unit connected to the handle to adjust the resilient member to reach a torque value of the driving head; 
 an index unit having a second piece, a first index and a second index, the second piece, the first index and the second index being an integral part and movable longitudinally with a length change of the resilient member; the first index movably engaged with the slot of the at least one ring; the resilient member extends through the at least one ring 
 a display unit fixed to the handle and having a display member, a calculation member and at least one movement sensor which detects a movement distance of the first index and generates a signal which is calculated by the calculation member and transferred into a torque value displayed in the display member, and 
 a scale member being a transparent member and having marks thereon, the scale member located to the handle and corresponding to the second index, the mark being pointed by the second index being the torque value. 
 
     
     
       12. The torque wrench as claimed in  claim 11 , wherein there are four movement sensors and the first index has multiple parallel first lines and second lines, the first and the second lines are detected by the movement sensors. 
     
     
       13. The torque wrench as claimed in  claim 11 , wherein the first index has value marks which are matched with the marks on the scale member.